1. Field of the Invention
This invention relates to a method and apparatus for sorting out from a large quantity of seeds which have been kept under conditions well adapted for germination such seeds which then have started the germination process.
2. Prior Art
Dry seeds, i.e. seeds having a relatively low moisture content, are usually used for sowing. This means that a relatively long time elapses from sowing until the seed has absorbed sufficient moisture to be able to shoot out germs. It has already been realised that this time can be appreciably reduced by allowing the seeds to absorb moisture and start the germination process before sowing. In a common method for this purpose, the seeds have been comletely immersed in a vessel containing water. Although the seeds undoubtedly absorb the water and start the germination process, their subsequent development tends to cease, and this would appear to be due to the fact that they do not get sufficient oxygen. Seeds not only require considerable humidity but also good supply of oxygen for their development. Pretreatment of seeds as above can be interrupted at the required stage, for example immediately before the seed hull bursts and germs appear. This means that the heartiness of the seeds remains.
Plant growing could also be made more efficient if only those seeds which will result in a plant could be selected before sowing. This would do away with empty gaps in sown rows or empty pots in the case of growing plants in pots, without any thinning being necessary due to more than one seed being sown in each place for safety. To fulfil these requirements, it must be possible to separate those seeds which have commenced the germination process on contact with moisture from those seeds which are unable to germinate for some reason. In prior growing methods it has not been possible to carry out such sorting before the seeds have resulted in small plants. However, this makes considerable demands on storage space, inter alia, and subsequent handling of the plants, and this makes it difficult, for example, to mechanize the planting in a natural environment.
It is therefore desirable for the seed germination to be effected in such a manner that germinating seeds can be sorted out from non-germinating seeds easily and at the earliest possible stage. Sorting should be carried out at a stage such that the seeds selected for sowing can be handled in substantially the same way as non-pregerminated seeds. Sorting must also be possible at very high speed.